Biology subjects

Pontes, G.

Publications and source records attributed to Pontes, G..

5 recordsLinked to original sources

bioRxiv2023

Hunger- and thirst-sensing neurons modulate a neuroendocrine network to coordinate sugar and water ingestion

Consumption of food and water is tightly regulated by the nervous system to maintain internal nutrient homeostasis. Although generally considered independently, interactions between hunger and thirst drives are important to coordinate competing needs. In Drosophila, four neurons called the Interoceptive Subesophageal zone Neurons (ISNs) respond to intrinsic hunger and thirst signals to oppositely regulate sucrose and water ingestion. Here, we investigate the neural circuit downstream of the ISNs to examine how ingestion is regulated based on internal needs. Utilizing the recently available fly brain connectome, we find that the ISNs synapse with a novel cell type Bilateral T-shaped neuron (BiT) that projects to neuroendocrine centers. In vivo neural manipulations revealed that BiT oppositely regulates sugar and water ingestion. Neuroendocrine cells downstream of ISNs include several peptide-releasing and peptide-sensing neurons, including insulin producing cells (IPC), crustacean cardioactive peptide (CCAP) neurons, and CCHamide-2 receptor isoform RA (CCHa2R-RA) neurons. These neurons contribute differentially to ingestion of sugar and water, with IPCs and CCAP neurons oppositely regulating sugar and water ingestion, and CCHa2R-RA neurons modulating only water ingestion. Thus, the decision to consume sugar or water occurs via regulation of a broad peptidergic network that integrates internal signals of nutritional state to generate nutrient-specific ingestion.

neuroscience↗

bioRxiv2022

Food recognition in a blood-feeding insect: characterization of the pharyngeal taste organ

BackgroundObligate blood-feeding insects obtain the nutrients and water necessary to ensure survival from the vertebrate blood. The internal taste sensilla, situated in the pharynx, evaluate the suitability of the ingested food. Here, through multiple approaches, we characterized the pharyngeal organ (PO) of the hematophagous kissing bug Rhodnius prolixus to determine its role in food assessment. The PO, located antero-dorsally in the pharynx, comprises 8 taste sensilla that become bathed with the incoming blood. ResultsWe showed that these taste sensilla house gustatory receptor neurons projecting their axons through the labral nerves to reach the subesophageal zone in the brain. We found that these neurons are electrically activated by relevant appetitive and aversive gustatory stimuli such as NaCl, ATP and caffeine. Using RNA-Seq, we examined the expression of sensory-related gene families in the PO. We identified gustatory receptors, ionotropic receptors, transient receptor potential channels, pickpocket channels, opsins, takeouts, neuropeptide precursors, neuropeptide receptors and biogenic amine receptors. RNA interference assays demonstrated that the pickpocket channel Rproppk014276 is necessary for salt detection during feeding. ConclusionWe provide evidence of the role of the pharyngeal organ in food evaluation. This work shows the first comprehensive characterization of a pharyngeal taste organ in a hematophagous insect.

neuroscience↗

bioRxiv2021

Evolution of the insect PPK gene family

Insect Pickpocket (PPK) receptors mediate the detection of stimuli of diverse sensory modalities, therefore having a relevant role for environmental sounding. Notwithstanding their relevance, studies on their evolution are scarce. We have analyzed the genomes of 26 species belonging to 8 insect orders (Blattodea, Orthoptera, Hemiptera, Phthiraptera, Hymenoptera, Lepidoptera, Coleoptera, and Diptera) to identify their PPK repertoires and study the evolution of this gene family. PPKs were detected in all genomes analyzed, with a total of 578 genes identified that distributed in 7 subfamilies. Our phylogenetic analysis allowed clarifying that the ppk17 gene appears to be the most divergent family member, composing a new group designed as subfamily VII. According to our analysis, PPKs evolved under a birth-and-death model that generated lineage-specific expansions usually located in clusters and the effect of strong purifying selection was seen for several orthogroups. Subfamily V was the largest one, presenting half of all PPKs studied, including a mosquito-specific expansion that can be considered a new target for pest control. Consistently with their sensory role, PPKs present a high gene turnover that generated considerable variation in the size of insect repertoires: Musca domestica (59), Blattella germanica (41), Culex quinquefasciatus (48), and Aedes albopictus (51) presented the largest PPK repertoires, while Pediculus humanus (only ppk17), bees and ants (6-9) had the smallest ones. The expansions identified in M. domestica and Bl. germanica also show promise as specific targets for controlling these nuisance insects. Our phylogenetic analysis revealed a subset of prevalent PPKs across insect genomes, suggesting a very conserved function that resembles the case of antennal ionotropic receptors. Finally, we identified new highly conserved residues in the second transmembrane domain that may be key for receptor function. Besides, more than a hundred PPK sequences presented calmodulin binding motifs, suggesting that at least some members of this family may amplify sensory responses as previously proposed for D. melanogaster ppk25. Overall, our study is a first attempt to characterize the evolutionary history of this family of sensory receptors, revealing relevant unknown features and clade-specific expansions.

genomics↗

bioRxiv2021

Salty surfaces deter feeding in a blood-sucking disease vector

Salts are essential nutrients required for many physiological processes, and deficient or excessive salt results in adverse health problems. Taste is the ultimate sensory modality involved in resource quality assessment, resulting in acceptance or rejection. Here, we show that detection of high-salt substrates by a salt-sensitive antennal gustatory receptor neuron, S1-GRN, results in feeding avoidance in the hematophagous bug Rhodnius prolixus. Knock-down of two antennal-expressed amiloride-sensitive pickpocket channel receptors (PPKs; RproPPK014276 and RproPPK28) using RNA interference, prevents avoidance of bugs to high-salt substrates. Tracing antennal GRNs to the central nervous system reveals the antennal lobes as a gustatory processing center. The identification of the gustatory basis of high-salt detection in a blood feeder provides novel targets to prevent biting and feeding, as well as to promote substrate avoidance in a relevant disease vector. Significance StatementDetection of aversive gustatory stimuli induces avoidance responses in animals. Avoidance acquires particular interest if it reduces the biting rates of blood-feeding insects of medical relevance. Here we describe the molecular and physiological basis of high-salt detection in the blood-sucking disease vector Rhodnius prolixus. We show that detection of high-salt substrates through two PPK receptors expressed in an antennal gustatory receptor neuron produces feeding avoidance. Understanding these gustatory-driven aversive responses allows the hitherto overlooked use of gustatory molecules as a complement to known olfactory repellents.

physiology↗

bioRxiv2017

Analysis of the immunological biomarker profile during acute Zika virus infection reveals the overexpression of CXCL10, a chemokine already linked to neuronal damage

Infection with Zika virus (ZIKV) manifests in a broad spectrum of disease ranging from mild illness to severe neurological complications. To define immunologic correlates of ZIKV infection, we characterized the levels of circulating cytokines, chemokines and growth factors in 54 infected patients of both genders, at five different time-points after symptoms onset using microbeads multiplex immunoassay; statistical analysis and data mining compared to 100 age-matched controls. ZIKV-infected patients present a striking systemic inflammatory response with high levels of pro-inflammatory mediators. Despite the strong inflammatory pattern, IL-1Ra and IL-4 are also induced during acute infection. Interestingly, the inflammatory cytokines, IL-1{beta}, IL-13, IL-17, TNF-, IFN-{gamma}; chemokines, CXCL8, CCL2, CCL5; and the growth factor G-CSF display a bimodal distribution accompanying viremia. While this is the first manuscript to document bimodal distributions of viremia in ZIKV infection, bimodal viremia has been documented in other viral infections with primary viremia peaks during mild systemic disease and a secondary viremia with distribution of the virus to organs and tissues. Moreover, biomarker network analysis demonstrated distinct dynamics in consonance with the bimodal viremia profiles at different time-points during ZIKV infection. Such robust cytokine and chemokine response has been associated with blood-brain barrier permeability and neuroinvasiveness in other flaviviral infections. High-dimensional data analysis further established CXCL10, a chemokine involved in fetal neuron apoptosis and Guillain-Barre syndrome, as the most promising biomarker of acute ZIKV infection for a potential clinical application.\n\nAuthor SummaryInfection with Zika virus manifests in a broad spectrum of disease ranging from mild illness to severe neurological complications. This study characterized the levels of circulating cytokines, chemokines and growth factors in Zika-infected patients showing an inflammatory immune response. Specifically, this study identified a chemokine, CXCL10, known to be involved in fetal neuron apoptosis and Guillain-Barre syndrome, as the most promising biomarker to characterize acute Zika virus infection.

immunology↗